Researchers Andrew Miller, MD and William P. Timmie, PhD of Emory University, and Charles Raison, MD, previously at Emory University and now at the University of Arizona, are taking an evolutionary approach to studying the relationships between depression and immune system function.

Due to findings that much of the genetic variation observed in depression is related to changes in immune system function, specifically in inflammation, they propose that this would have offered an evolutionary benefit in terms of being able to fight infections. For example, there are numerous behavioral factors related to depressions that may have been adaptive in terms of restricting or containing infection, including social avoidance and fatigue/inactivity.